With reference to FIG. 1, an example of a conventional medium voltage switchgear is shown generally at 10. As used herein, the terms “medium voltage switchgear” refers to switchgear rated for operation up to and including 15 kV . In general, switchgear 10 comprises an enclosure, such as metal-clad enclosure 12, for housing the switchgear components. Enclosure 12 may contain one or more separate compartments, such as circuit breaker compartment 14, main bus compartment 16, and cable compartment 18. The bus and cable compartments can be formed as a single compartment. Switchgear 10 contains one or more circuit breakers, generally indicated at 20. In the embodiment shown, circuit breaker 20 is a three-pole drawout type circuit breaker. Circuit breaker 20 is connected to primary contacts that are supported by primary conductor bushings 22 that are connected to current-carrying bus bars 24.
In this typical switchgear arrangement, the current transformers 26 are mounted in the circuit breaker compartment 14 while the primary contact are carried by the bushing 22 located in a separate bus and cable compartments 16, 18. This configuration increases design and assembly complexity. At higher current ranges, the length of a bushing 22 associated with a primary contact must be increased to maintain sufficient creepage distance, adding to the overall switchgear depth.
Thus, there is a need to provide a bushing structure that combines the functionality of a primary contact with a current transformer primary conductor and a post insulator to reduce the depth and width of the switchgear.